Question: 4 crayons cost $5.68. Which equation would help determine the cost of 9 crayons?
There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 4 crayons. We want to know the cost of 9 crayons. We can write the numbers of crayons as a proportion: $\dfrac{4}{9}$ We know 4 crayons costs $5.68. We can let $x$ represent the unknown cost of 9 crayons. The proportion of these costs can be expressed as: $\dfrac{\$5.68}{x}$ The cost changes along with the number of crayons purchased, and so the two proportions are equivalent. $\dfrac{4}{9} = \dfrac{\$5.68}{x}$